Hyperthyroidismis the term for overactive tissue within the thyroid gland, resulting in overproduction and thus an excess of circulating free thyroid hormones: thyroxine (T4), triiodothyronine(T3), or both.

Etiology and Pathophysiology

■ Diffuse toxic goiter (Graves’ disease) or autoimmune condition secondary to infection, crisis or stress. This leads to ↓thyroid-specific suppressor T-cell lymphocytes, which leads to ↑T3 (triiodothyronine) and/or ↑T4 (thyroxine). The result is an ↑metabolic rate and sensitivity tocatecholamines

■ Sudden severe hyperthyroidism is called thyrotoxicosis or thyroid storm

■ Hyperthyroidism generally occurs between 20 and 40yr old and is morecommon in females